US3748557A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit for short reverse operation of a motor in a dictating machine or the like
Assignee: Grundig EMV Elektromechanische Versuchsanstalt Max Grundig GmbH
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Filing: 1972-07-19
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Granted: 1973-07-24
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Expires: 1992-07-19
Abstract
Abstract A motor control circuit is shown having two transistors of opposite conductivity type connected in series between power supply terminals and with the motor connected between a switch and the common terminal of the transistors. The switch can be connected to either the positive or negative power supply terminals. An additional transistor is connected in a monostable multivibrator circuit with the transistor that is conductive during reverse operation of the motor. An additional switch connects a pulse to the monostable multivibrator when the main switch is set for forward rotation of the motor. This pulse puts the multivibrator into its unstable state to reverse current through the motor until the multivibrator returns to its stable state.
Inventors
- 👤 R Mittelstaedt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 06:23
CPC Classifications
G; G11; G11B; G11B15/00; G11B15/18; G11B15/44; H; H02; H02P; H02P7/00; H02P7/03
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
363 words
A circuit for controlling the direction of rotation of a direct current motor, said circuit comprising: A. positive and negative direct current power supply terminals; B. a direct current motor comprising first and second terminals to receive direct current to cause the motor to run in either direction according to the direction of flow of said current; C. first and second transistors of opposite conductivity type having their emitters connected to said positive and negative power supply terminals, respectively, and their collectors connected to an intermediate terminal and to said first terminal of said motor, whereby the emitter-collector circuits of said transistors are connected in current-carrying polarity between said power supply terminals; D. first switching means connected to said second terminal of said motor to connect said second terminal alternatively to said positive and negative terminals, the base electrode of said first transistor being connected to said switching means to make said first transistor conductive when said switching means is connected to one of said power supply terminals and non-conductive when said switching means is connected to the other of said power supply terminals; E. second switching means connected to said first switching means to make said first transistor non-conductive when said first transistor is made conductive by said first switching means; and F. circuit means connected to the base of said second transistor to cause said second transistor to become conductive when said first transistor is made non-conductive by said first switching means and to become temporarily conductive when said first transistor is made non-conductive by said second switching means, said circuit means comprising: 1. a third transistor connected to said second transistor so as to form a monostable multivibrator which is stable when said third transistor is conductive and said second transistor is non-conductive, said third transistor being held nonconductive by said first switching means when said first transistor is made non-conductive by said first switching means, and 2. a capacitor connected in series between the base of said second transistor and said second terminal of said motor so as to set said monostable multivibrator to its unstable state when said first transistor is made non-conductive by said second switching means.
Claim 2
Dependent Claim
363 words
A circuit for controlling the direction of rotation of a direct current motor, said circuit comprising: A. positive and negative direct current power supply terminals; B. a direct current motor comprising first and second terminals to receive direct current to cause the motor to run in either direction according to the direction of flow of said current; C. first and second transistors of opposite conductivity type having their emitters connected to said positive and negative power supply terminals, respectively, and their collectors connected to an intermediate terminal and to said first terminal of said motor, whereby the emitter-collector circuits of said transistors are connected in current-carrying polarity between said power supply terminals; D. first switching means connected to said second terminal of said motor to connect said second terminal alternatively to said positive and negative terminals, the base electrode of said first transistor being connected to said switching means to make said first transistor conductive when said switching means is connected to one of said power supply terminals and non-conductive when said switching means is connected to the other of said power supply terminals; E. second switching means connected to said first switching means to make said first transistor non-conductive when said first transistor is made conductive by said first switching means; and F. circuit means connected to the base of said second transistor to cause said second transistor to become conductive when said first transistor is made non-conductive by said first switching means and to become temporarily conductive when said first transistor is made non-conductive by said second switching means, said circuit means comprising: 1. a third transistor connected to said second transistor so as to form a monostable multivibrator which is stable when said third transistor is conductive and said second transistor is non-conductive, said third transistor being held nonconductive by said first switching means when said first transistor is made non-conductive by said first switching means, and 2. a capacitor connected in series between the base of said second transistor and said second terminal of said motor so as to set said monostable multivibrator to its unstable state when said first transistor is made non-conductive by said second switching means.
Claim 3
Dependent Claim
42 words
a capacitor connected in series between the base of said second transistor and said second terminal of said motor so as to set said monostable multivibrator to its unstable state when said first transistor is made non-conductive by said second switching means.
Claim 4
Dependent Claim
42 words
a capacitor connected in series between the base of said second transistor and said second terminal of said motor so as to set said monostable multivibrator to its unstable state when said first transistor is made non-conductive by said second switching means.
Claim 5
Dependent Claim
39 words
The motor control circuit of claim 1 in which said monostable multivibrator comprises a time constant to control the duration of the time that said monostable multivibrator remains in its unstable state, said time constant comprising a variable resistor.
Claim 6
Dependent Claim
57 words
The motor control circuit of claim 1 comprising, in addition, third switching means connected to said first switching means to operate simultaneously therewith and electrically connected to said third transistor to render said third transistor non-conductive when said first and third switching means are switched to a condition to cause said motor to run continuously in reverse.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-23 | 1977-01-22 | 1977-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-23 | 1981-01-22 | 1981-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-23 | 1985-01-22 | 1985-07-24 | $7700.00 | Window Closed / Lapsed |